Having written this ranking, I'm wondering if sweet 16 is the cost at which one can get the most ship for their points. Yes, there are some real stinkers at this cost, like Lusca and Drowned Man, but many of the rest are pretty solid, or sometimes, even among the best ships out there.

10. USS Mercury
Any time the honorable mention Nautilus is brought up, so is USS Mercury, along with her windcatcher counterpart. Mercury's ability is inferior, but her guns, faction, and crew selection are far better, so she edges Nautilus out. She too can be made a tricky devil with Christian Fiore, or with Gus Schultz, because last I knew, submarines can't be towed and recovered by your enemies...

9. Divine Dragon
Divine Dragon is one of two six-masters not a part of the Jade Rebellion that were released in Ocean's Edge, and she strangely shares a name with a turtle ship. Her gun ranks are pretty lame, though she does get a built-in world hater to buff them. On the other hand, this leaves your options for further buffing her guns limited, so she's almost best built as a boarder, given her size and the myriad Cursed crew with such emphasis.

8. Le Superbe
An understated ship, I daresay. Above average in most respects, with good speed for her size, a large cargo hold, good armament, and an ability that may be useful in clustered fights. The French don't have a ton that can spice her up, but she doesn't need much to shine. At the same time, her general lack of exploitable extreme strengths makes her hard to use for outrageous strategies, limiting her upper potential.

7. Harbinger
Hot take: DJC Harbinger is a really solid ship. Her cargo space and armament are comparable to Le Superbe, but I think her ability is significantly more useful, and she has almost unparalleled crew selection. The lost speed and gun range is offset by her capability to be a superior brawler, which is often what is needed of ships this size.

6. HMS Gallows
HMS Gallows is a straightforward, no-nonsense warship that happens to have a hold large enough to turn her into a hybrid. Quad 1L guns with a captain aboard and 4 cargo remaining give her plenty of options in all game sizes. Thomas Gunn is good if you're feeling cheap, and I suppose Carbon Charlie is an option if you feel like doing some weird stuff with Gallows.

5. El Cristal del Obispo/HMS Dauntless/La Ville de Paris
Now this one's strange, because we're faced with three five-masters of the same point cost with identical abilities. All have S guns at either end and L guns in the middle, as well as 5 cargo. As you go from left to right, they lose speed in favor of better guns. La Ville de Paris sacrifices so much speed in the name of having the best guns that I think she's not quite as good as the other two, but due to her similarity, I had to include her here as an honorable mention. Between Obispo and Dauntless, I would choose the latter due to England's wealth of crew options for gunships, but there are arguments to be made for Obispo too—as acknowledged by a7xfanben in his ranking of the best Spanish gunships.

4. Deliverance
The Ocean's Edge variant of Deliverance is tied for the title of fastest five-master with San Cristobal and HMS Swallow. While her starting cost is cheaper than either, to get her to achieve the L+S+S+S speed of which she is capable, you must attain multiple rare RotF promo crew, including Crimson Angel and Griffin. Put them on board with a helmsman, and you're at that speed, but it'll cost you 31 points, as opposed to Swallow's 29 and Cristobal's 21.

Never mind that, Deliverance is still in possession of the fastest base move for any normal five-master, and an awesome crew selection, so go hog wild filling her hold with the best pirate crew in your collection. We should be thankful that a ship so close to the top is so common.

3. Blackwatch
Blackwatch is a standout ship from a largely mediocre set, with her two leading 1L guns, and trailing 2L guns. The fact that she has a respectable hold space and useable move on top of her nasty armament makes her a true gem.

2. USS Kettering
Kettering is an oddity. She's the only American longship, and is the fastest of all longships, as well as one of the fastest ships in her set. Her hold, size, and cannon ranks are nothing special for her cost, but she has a cruel ability, and the longship keyword doubles her firepower up to 6 3L guns, easily buffed by American crew such as Brent Rice or others to 2L. Just enough hold space is available for the necessary crew, and she'll be a nightmare to fight no matter the game size.

1. Le Bonaparte
Yeah, I'm not sure anyone expected otherwise. Bonaparte is one of only two four-masters to receive this ability, the other being the inferior Nubian Prince. She's quick, competently armed, durable, and almost impossible to shoot. Again, just enough space is present that she can be crewed dangerously, despite the generally uninteresting French crew selection.

Now this one is tough. I had to consult my Top 10 Gunships Ranking thread (which may need revision) to check some stuff out... but here we're ranking them overall as ships, not just purely as gunships. Otherwise my list would follow that one more.

My rankings:
1. Le Bonaparte
stupid thing I'm so biased against this trash that I really have a hard time even acknowledging it.
2. Blackwatch / HMS Gallows
-Blackwatch has a slight edge in being a pure gunship, Gallows gets the edge for hybrid use.
3. USS Kettering
-Hmmm. Not sure if this should be higher on this list AND my best gunships list... the durability is still too much of an issue though I think.
4. Le Superbe
-No surprise considering my gunships list. Better cannons, cargo and ability than Deliverance. Tough choice though!
5. Deliverance
-I think you've become too obsessed with LE Griffin.
6. Divine Dragon
-Basically 6 rank-3 cannons with a fantastic link and plenty of cargo and speed for a ship like this. With the lack of Cursed world haters, I don't see the need to try and make her cannons any better. I have seen this thing dominate various campaigns and situations, though I might be biased due to that history and the crew setups I usually put aboard. (such as Davy Jones ... )
7. HMS Dauntless / El Cristal del Obispo
-(Dauntless) I need that firepower haha. Gets overshadowed by the Endeavour a bit, but a very good gunship.
The Cristal is nice and has underrated potential as a hybrid. I can imagine Luis Zuan / Dominic Freda /helmsman/oarsman in a largish game... oof.
8. Harbinger
-I wouldn't blame someone for putting this as high as 6. Overshadowed by the original, and as a result one of the most underrated Pirate ships out there I would say.
9. La Ville de Paris
-LOVE the ship, I mean come on! XD Yay Wizkids for that. But really, this is supposed to be a mostly objective ranking of the best ships at this cost, and speed matters a LOT. Reminds me of my thematically favorite ship, HMS Lord Algernon . Realistic and cool, just not perfect for gameplay.
10. USS Mercury
-No disagreement here, especially with my "personal" difference on 2L vs 3S guns. (3S have been my nemesis many times in the past...)
In a strange way, the Nautilus' great ability isn't always that useful to her. A lot of times I've seen her just underwater for ramming, and as an escort for larger ships in big games. I feel like when you go after either of these, you go after them hard. As in, with multiple cancellers. XD This is often necessary just to deal with them. As a result, with enough cancelling the difference between abilities can be somewhat (literally) negated.